Self-position measuring terminal

ABSTRACT

An information processing apparatus including a positioning unit that determines a position of the information processing apparatus based on an external signal; a sensor unit that detects a change in position of the information processing apparatus; and a processing unit that measures, according to a change in position detected at the sensor unit, an amount of displacement of the information processing apparatus from a first time when the positioning unit starts to determine the position of the information processing apparatus to a second time when the positioning unit completes determining the position of the information processing apparatus; and identifies a position of the information processing apparatus at the first time by compensating the position of the information processing apparatus determined by the positioning unit at the second time with the amount of displacement of the information processing apparatus.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of the earlier filing date ofU.S. Provisional Patent Application Ser. No. 61/597,204 filed on Feb.10, 2012, the entire contents of which is incorporated herein byreference.

BACKGROUND Field of the Disclosure

The present disclosure relates to a self-position measuring terminalthat is applied to a case in which the Global Positioning System (GPS)is used to determine the position of the terminal itself.

FIELD OF THE DISCLOSURE

A known conventional technology to measure the position of a terminalitself (referred to below as the self-position) uses GPS. GPS is apositioning system that receives radio waves (GPS signals) from aplurality of GPS satellites and obtains the current self-position(latitude and longitude) of a terminal in which a GPS receiver isincorporated. Accordingly, mobile communication apparatuses (mobileterminals), imaging apparatuses (cameras), and other apparatuses thatincorporate a GPS receiver could add information about the latitude andlongitude at an imaging site to image data and the like. This type ofinformation, about the latitude and longitude at an imaging site, whichis added to the image data and the like, is referred to as a geotag.

When the geotag is read from the image data, the latitude and longitudeat the imaging site can be obtained, so it is possible to record theimaging site on an electronic map in correspondence to the latitude andlongitude. Accordingly, technologies to improve the precision ofpositions obtained by the use of GPS have been studied.

U.S. Pub. 2008/0094242 describes a technology in which a terminalreceives GPS signals from satellites and also receives signals thatimprove resolution from geological sensors and acceleration sensors tomeasure the roll, pitch, and yaw of the terminal and interpolate theposition of the terminal.

“A Study on Self-Position Detection of a Moving Object by anAcceleration Sensor”, Jan. 22, 2010, Okayama University, describes atechnology in which a moving body detects the angles of a roll, pitch,and yaw and accelerations in the three directions of the X, Y and Z axesto detect the position of the moving body.

SUMMARY

Although, as described above, GPS signals can be used to check theself-position of a terminal and record the self-position on capturedimage data, the following problems have also been known.

(1) First problem: It may take time from when the determination of theself-position is started until the self-position is identified.

(2) Second problem: The precision of the identified self-position may below (the self-position may be inaccurate). However, the precision of theself-position is improved with time.

Since the above first and second problems depend on the positioningenvironment (the number of GPS satellites, positional relationshipbetween the self-position and the satellites, presence or absence of anobstacle around the self-position, or the like), some countermeasuresare needed.

An example of a positioning process in which a self-position isdetermined with low precision will be described below with reference todisplay examples of screens displayed on the display unit (displaypanel, for example) of a mobile terminal.

FIGS. 12A and 12B illustrate an example of a map and a self-positiondisplayed on the display unit of a mobile terminal. FIG. 12A illustratesa display example at the start of self-position determination, and FIG.12B illustrates a display example after a lapse of a prescribed time.

As illustrated in FIG. 12A, when the user starts self-positiondetermination at a certain place, a large circle is displayed,indicating that error in positioning precision in the determination ofthe self-position is 40 meters or less. The “positioning precision” is acircular error probability, which represents a range in which a mobileterminal having a GPS receiver is present with a certain probability.This positioning precision is calculated by the mobile terminalaccording to the intensity of the GPS signals received, the receptionenvironment, and the like.

The place at which the user is actually present is indicated with astar. This star is a mark not displayed on the display unit. This markindicates that in reality, the user is outside a building. Even if theuser is outside the building, however, an arrow is displayed at thecenter of a circle and within the building, the arrow indicating thatthe user is assumed to be present there. The mobile terminal continuesto determine the self-position by the use of GPS signals received fromGPS satellites, gradually increasing the positioning precision. At thattime, the dashed circle in FIG. 12A is displayed so as to become small.

After that, when the positioning precision becomes sufficiently high,for example, when the circular error probability becomes 1 meter orless, the arrow overlaps the small dashed circle, terminating thedetermination of the self-position. Since the user travels outsidebuildings on foot from the situation in FIG. 12A to the situation inFIG. 12B, the position of the user at the end of positioning differsfrom the position at the start of positioning.

Thus, the position determined at the start of positioning often differsfrom the actually determined position of the user, so there have beenmany cases in which even when a geotag is added to image data capturedby a camera or the like, the imaging site is not indicated accurately.

Accordingly, the inventor has recognized the need to measure theself-position accurately at which GPS-based positioning is started.

According to an embodiment of this disclosure, an information processingapparatus is disclosed that includes a positioning unit that determinesa position of the information processing apparatus based on an externalsignal; a sensor unit that detects a change in position of theinformation processing apparatus; and a processing unit that measures,according to a change in position detected at the sensor unit, an amountof displacement of the information processing apparatus from a firsttime when the positioning unit starts to determine the position of theinformation processing apparatus to a second time when the positioningunit completes determining the position of the information processingapparatus; and identifies a position of the information processingapparatus at the first time by compensating the position of theinformation processing apparatus determined by the positioning unit atthe second time with the amount of displacement of the informationprocessing apparatus.

According to this disclosure, even if an accurate self-position has notbeen accurately determined at the start of GPS-based positioning, theself-position at the start of positioning can be accurately identifiedby subtracting a displacement from an accurate self-position determinedafter a lapse of a certain time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary internal structureof a mobile terminal in a first embodiment of this disclosure.

FIG. 2 illustrates an example in which when GPS-based positioning iscarried out, a self-position at the start of positioning is identifiedin the first embodiment of this disclosure.

FIG. 3 is a flowchart illustrating an example of processing in which themobile terminal in the first embodiment of this disclosure identifiesits self-position at which positioning was started.

FIG. 4 is a flowchart illustrating a detailed example of processing instep S4 in FIG. 3.

FIG. 5 illustrates an example in which the self-position at the start ofpositioning is identified when precision in GPS-based positioning in asecond embodiment is low.

FIG. 6 is a flowchart illustrating an example of processing in which themobile terminal in the first embodiment of this disclosure identifiesits self-position at which positioning was started.

FIG. 7 is a flowchart illustrating a detailed example of processing instep S24 in FIG. 6.

FIGS. 8A and 8B illustrate an example in which the mobile terminal in athird embodiment of this disclosure travels from point A to point Z.

FIGS. 9A-9D illustrate a first display example of a user interfacedisplayed on a display unit during the determination of theself-position in the first to third embodiments of this disclosure.

FIGS. 10A-10C illustrate a second display example of the user interfacedisplayed on the display unit during the determination of theself-position in the first to third embodiments at the time of imagingwith a captured image displayed.

FIG. 11 illustrates a third display example of the user interface usedwhen the travel trace of the mobile terminal is displayed on the displayunit.

FIGS. 12A and 12B illustrate examples of a map and a self-positiondisplayed on a display unit of a conventional mobile terminal.

DETAILED DESCRIPTION

Modes that embody this disclosure (referred to below as embodiments)will be described below in the following order.

1. First embodiment (example of processing to identify a self-positionat which positioning was started in a case in which it takes time fromwhen positioning was started until the current position is identified)

2. Second embodiment (example of processing to identify theself-position at which positioning was started in a case in whichpositioning precision at the start of positioning is low)

3. Third embodiment (variation of the method of determining theself-position)

4-1. First to third embodiments (first display example of a userinterface)

4-2. First to third embodiments (second display example of the userinterface)

4-3. First to third embodiments (third display example of the userinterface)

5. Variation

1. First Embodiment

[Example of Processing to Identify a Self-Position at which Positioningwas Started in a Case in which it Takes Time from when Positioning wasStarted Until the Current Position is Identified]

A first embodiment of this disclosure will be described with referenceto FIGS. 1 to 4. In this embodiment, an example in which the embodimentis applied to a mobile terminal 1 that includes a GPS receiver 3configured to receive GPS signals and determines the self-position willbe described. The mobile terminal 1 implements a self-positiondetermination method, which is carried out cooperatively by internalblocks described later, by having a computer execute a program.

FIG. 1 is a block diagram illustrating an exemplary internal structureof the mobile terminal 1.

The mobile terminal 1 includes a manipulation input unit 2 to which theuser supplies a manipulation input and a GPS receiver 3 that receivesGPS signals from GPS satellites. The mobile terminal 1 also includes asensor unit 4 including various type of sensors as well as a camera 5that has an optical lens system and an imaging device (not shown) tooutput image data to a memory 8. The mobile terminal 1 also includes adata processing unit 6 that processes various types of data, a displayunit 7, on which a touch panel is placed, that displays still pictures,moving pictures, icons, and other images, and the memory 8 that storesvarious types of programs, data, and the like.

The data processing unit 6 includes a time managing unit 11, apositioning managing unit 12, a positioning precision monitoring unit13, a self-position identifying unit 14, a displacement measuring unit15, an imaging unit 16, and a positional information writing unit 17.

The manipulation input unit 2 is structured with a touch panel and thelike. The user can execute various types of functions of the mobileterminal 1 by touching the surface of the touch panel with a finger, astylus pen, or the like. However, the manipulation input unit 2 mayaccept user's manipulation inputs through buttons and a dial instead ofincluding the touch panel.

The GPS receiver 3 outputs GPS signals (positioning information)received from a plurality of GPS satellites to the data processing unit6. The GPS receiver 3 can also appropriately correct a current timeaccording to time information included in the GPS signals.

The sensor unit 4 includes an electronic compass 21 that detects earth'smagnetism and thereby detects a direction in which the mobile terminal 1travels, an acceleration sensor 22 that detects the force of gravity oracceleration and thereby detects the travel speed of the mobile terminal1, and a gyro sensor 23 that detects an angular velocity and therebydetects the rotational travel of the mobile terminal 1. The traveldirection, travel speed, and the amount of rotational travel will becollectively referred to as the mount of change. Upon detection of theamount of change of the terminal 1, the sensor unit 4 outputs the amountof change detected by the sensors to the displacement measuring unit 15as sensor data.

As an imaging device (not shown) included in the camera 5, chargecoupled devices (CCD) imager or a complementary metal oxidesemiconductor (CMOS) image sensor is used, for example. The camera 5captures still pictures or moving pictures; it can drive not only theoptical lens system but also a shutter, a diaphragm mechanism, and thelike, which are not shown, to photograph a subject appropriatelyaccording to the photograph environment of the subject.

The function of each processing block included in the data processingunit 6 is implemented by a software program executed by a centralprocessing unit (CPU) (not shown).

The time managing unit 11 manages time T1 at which the determination ofthe self-position starts and time T2 at which the determination isterminated.

The positioning managing unit 12 determines the self-position accordingto GPS signals received from GPS satellites, manages completion ornon-completion of positioning as a positioning state, and manages thedetermined self-position.

The positioning precision monitoring unit 13 monitors the precision inGPS-based positioning, which changes with time, according to positioningerror in the self-position determined by the use of GPS signals.

To identify the self-position at which positioning was started, theself-position identifying unit 14 acquires, from the positioningmanaging unit 12, the self-position at which positioning was started andcarries out compensation from the self-position acquired from thepositioning managing unit 12 after a lapse of a prescribed time by theuse of the amount of displacement. The self-position identifying unit 14also adds the self-position acquired at the start of GPS-basedpositioning to an image. The self-position identifying unit 14 alsoupdates the identified self-position at which positioning was startedand adds the updated self-position.

The displacement measuring unit 15 measures the amount of displacement,which is used to compensate the self-position at which the positioningmanaging unit 12 has started positioning, according to the amount ofchange of the mobile terminal 1, which was read from the sensor datareceived from the sensor unit 4. At that time, the displacementmeasuring unit 15 determines a travel direction and a traveled distancerelative to the self-position of the mobile terminal 1 at the start ofdetermination. The displacement measuring unit 15 assumes that a traveldirection and a traveled distance relative to a certain reference pointcan be accurately detected with error not exceeding a certain level.

The imaging unit 16 photographs a subject and creates an image includinga subject image. At that time, the imaging unit 16 adds processing toimage signals received from the camera 5 and controls a shutteroperation and the like. In addition, for example, the imaging unit 16can display an icon for the camera on the display unit 7 and can processimage data according to the command entered by manipulating themanipulation input unit 2.

The positional information writing unit 17 writes information about theself-position determined by the positioning managing unit 12 into thememory 8 when the imaging unit 16 carries out a shutter operation.

As the display unit 7, a liquid display panel or an organicelectro-luminescence (EL) display panel is used, for example. Thedisplay unit 7 may be formed with a main display and a sub-display,which is smaller in size than the main display.

A processing procedure for the mobile terminal 1 according to the firstembodiment of this disclosure to identify the self-position at whichpositioning was started will be briefly described below, the processingprocedure being executed when GPS-based positioning has not beencompleted.

(1) Time T1 at which GPS-based positioning has not been completed butthe self-position at which time is to be identified is held.

(2) Sensors are used to constantly determine the mount of change (traveldirection and traveled distance), starting from time T1.

(3) The self-position at time T1 is calculated from the self-position attime T2, at which GPS-based positioning has been completed, and theamount of change (travel direction and traveled distance) in the rangefrom time T1 to time T2.

FIG. 2 illustrates an example in which when GPS-based positioning iscarried out, a self-position at the start of positioning is identified.

As illustrated in (1) in FIG. 2, a time at which the determination ofthe self-position was started by the use of GPS is held. It is assumedhere that the user starts positioning at point A indicated at thelower-right in FIG. 2 and the time at which positioning starts isdenoted T1.

At this point in time, an accurate position at which the user isactually present having the mobile terminal 1 has not been identified.However, the mobile terminal 1 starts to determine the travel directionand traveled distance of the mobile terminal 1 relative to point A atwhich positioning was carried out at time T1. The sensor unit 4constantly determines the travel direction and traveled distance of themobile terminal 1, starting from time T1, as illustrated in (2) in FIG.2, and continues to send sensor data to the displacement measuring unit15. The displacement measuring unit 15 then accumulates the receivedsensor data in the memory 8.

After that, as illustrated in (3) in FIG. 2, the determination of theself-position is completed at time T2. The self-position identifyingunit 14 then carries out compensation by subtracting the amount ofdisplacement continued until positioning by the use of GPS signals hasbeen completed from the self-position at which positioning by the use ofGPS signals has been completed. Specifically, to identify an accurateself-position at time T1 from the self-position at point Z at the time(=T2) when GPS-based positioning has been completed, the self-positionidentifying unit 14 performs an inverse operation on the relative traveldirection and traveled distance of the mobile terminal 1, which wasdetermined and accumulated by the displacement measuring unit 15 in therange from time T1 to time T2.

FIG. 3 is a flowchart illustrating an example of processing in which themobile terminal 1 identifies its self-position at which positioning wasstarted.

First, the positioning managing unit 12 activates the GPS receiver 3 andstarts the determination of the self-position by the use of GPS. Theself-position identifying unit 14 then requires the positioning managingunit 12 to identify the self-position at time T1 (step S1).

The self-position identifying unit 14 then checks the positioning stateat the self-position (step S2). If positioning has been completed, theself-position identifying unit 14 acquires the self-position at time T1from the positioning managing unit 12 (step S3) and transfers theprocessing to step S9.

If positioning has not been completed, the positioning managing unit 12continues the determination of the self-position, and the displacementmeasuring unit 15 continues to measure the travel direction and traveleddistance of the mobile terminal 1, starting from point A at time T1(step S4). To determine whether the state of GPS-based positioning bythe positioning managing unit 12 was updated, the self-positionidentifying unit 14 then decides whether a positioning completion flag,which indicates whether the GPS-based determination of the self-positionhas been completed, is turned on or off (step S5).

If the GPS-based positioning state continues to be updated and GPS-basedpositioning has not been completed, in which case the positioningcompletion flag is turned off, the processing is returned to step S4 andis repeated. If the GPS-based positioning state has not been updated andGPS-based positioning has been completed, the positioning completionflag is turned on. At that time, at which the current time is T2, theself-position identifying unit 14 acquires the self-position at time T2from the positioning managing unit 12 as a first processing result (stepS6).

Next, the self-position identifying unit 14 acquires, from thedisplacement measuring unit 15, the travel direction and traveleddistance of the mobile terminal 1 in the range from time T1 to time T2as a second processing result (step S7). The self-position identifyingunit 14 then calculates the self-position at point A at time T1 from theacquired first and second processing results (step S8).

The self-position identifying unit 14 then identifies that point A attime T1 is an accurate self-position (step S9), terminating theprocessing. In step S9, the self-position at time T1 is updated by thefollowing processing. In this processing, point A at which imaging wascarried out with the camera 5 is used as a reference point and aposition relative to the reference point is acquired.

When the self-position is identified by, for example, using theacceleration sensor 22, the coordinates (X=Zx, Y=Zy) of point Z at whichpositioning was carried out at time T2 is obtained by GPS, and adistance (X=Tx, Y=Ty) traveled from time T1 to time T2 is obtained fromthe displacement measuring unit 15. The difference between parameters Xand Y is used as the compensated coordinates of point A. That is, therelative position can be obtained as the compensated coordinates(X=Zx−Tx, Y=Zy−Ty) of point A, which is a point at time T1.

Although an example in which the acceleration sensor 22 was used wasdescribed, it is also possible to obtain the relative position of themobile terminal 1 at point A by the use of another sensor. If theelectronic compass 21 is used, for example, when the displacementmeasuring unit 15 accumulates in the memory 8 a direction in which themobile terminal 1 faces with a lapse of time, a relative direction ofthe mobile terminal 1 at time T1 can be acquired. If the gyro sensor 23is used, when the displacement measuring unit 15 accumulates in thememory 8 an angle through which the mobile terminal 1 tilts with a lapseof time, the relative angle of the mobile terminal 1 at time T1 can beobtained.

FIG. 4 is a flowchart illustrating a detailed example of processing instep S4 in FIG. 3.

First, the positioning managing unit 12 acquires the current time duringdetermination from the time managing unit 11 (step S11), and receives aGPS signal from the GPS receiver 3 (step S12).

Next, the self-position identifying unit 14 identifies the self-positionduring travel (step S13). The displacement measuring unit 15 thenreceives sensor data from the sensor unit 4 (step S14). The sensor dataincludes a travel direction signal output by the electronic compass 21,a travel speed signal output by the acceleration sensor 22, and arotational travel signal output by the gyro sensor 23.

Next, the displacement measuring unit 15 measures the travel directionof the mobile terminal 1 according to the travel direction signal andaccumulates the time-series travel direction in the memory 8 (step S15).The displacement measuring unit 15 also measures the traveled distanceof the mobile terminal 1 according to the travel speed signal andaccumulates the traveled distance in the memory 8 (step S16).

Next, the positioning managing unit 12 decides whether GPS-basedpositioning has been completed for the current self-position (step S17).If the determination of the self-position has been completed, thepositioning managing unit 12 turns on the positioning completion flag(step S18). If the determination of the self-position has not beencompleted, the positioning managing unit 12 leaves the positioningcompletion flag turned off (step S9). The process in step S4 is thencompleted, and the sequence proceeds to step S5 in FIG. 3.

When the mobile terminal 1 according to the first embodiment describedabove cannot identify an accurate self-position at time T1 even by theuse of GPS, the mobile terminal 1 continues GPS-based positioning forthe current self-position. After that, when the mobile terminal 1 canidentify an accurate current self-position at time T2, the mobileterminal 1 obtains the self-position at the start of positioning, thatis, at time T1, from the current self-position at time T2 and the traveldirection and traveled distance detected by the sensor unit 4 in therange from time T1 to time T2. Accordingly, even if an accurateself-position cannot be obtained at the start of positioning, anaccurate self-position at which positioning was started can beidentified by subsequent positioning.

When the camera is used, in FIG. 2, the mobile terminal 1 writespositional information at point A identified by calculating the positionof point A from positional information at point Z at time T2 into theimage data of the subject captured at point A at time T1. Then, the usercan obtain accurate information about the place at which the usercarried out imaging with the camera.

2. Second Embodiment

[Example of Processing to Identify the Self-Position at whichPositioning was Started In a Case in which Positioning Precision at theStart of Positioning is Low]

Next, the mobile terminal 1 according to the second embodiment will bedescribed with reference to FIGS. 5 and 6. The mobile terminal 1according to this embodiment uses a threshold in GPS-based positioning;the mobile terminal 1 identifies the self-position at which positioningwas started from a determination result obtained when the threshold isexceeded. In the following description that corresponds to FIG. 1 andwas described in the first embodiment, like reference numerals are usedand detailed descriptions will be omitted.

A processing procedure for the mobile terminal 1 according to the secondembodiment of this disclosure to identify the self-position at whichpositioning was started will be briefly described below, the processingprocedure being executed when GPS-based positioning precision is low.

(1) Time T1 at which GPS-based positioning precision is low but theself-position at which time is to be identified is held.

(2) Sensors are used to constantly measure the travel direction andtraveled distance, starting from time T1. During this measurement,GPS-based positioning precision is constantly monitored.

(3) The self-position at time T1 is calculated from time T2, at whichthe GPS-based positioning precision exceeded a fixed threshold, whichhad been specified in advance, the self-position at time T2, and thetravel direction and traveled distance in the range from time T1 to timeT2.

FIG. 5 illustrates an example in which the self-position at the start ofpositioning is identified when precision in GPS-based positioning islow.

First, time (=T1) at which GPS-based positioning has not been completedbut the self-position at which time is to be identified is held, afterwhich positioning is started ((1) in FIG. 5). It is assumed here thatthe user starts positioning at point A indicated at the lower-right inFIG. 5 and the time at which positioning starts is denoted T1. At thattime, the position at which the user is actually standing is unknown.Since GPS-based positioning precision at the start of positioning islow, the positioning managing unit 12 carries out incorrect positioning,in which case the self-position is identified at point B ((2) in FIG.5).

However, the mobile terminal 1 starts to measure the travel directionand traveled distance of the mobile terminal 1, with reference to pointA. After that, the mobile terminal 1 determines the self-position atpoints A1, A2, . . . at fixed time intervals. Since the GPS-basedpositioning precision is increased with a lapse of time, the diameter ofthe dashed circle, which indicates the GPS-based positioning precisionmonitored by the positioning precision monitoring unit 13, becomes small((3) in FIG. 5). At that time, the displacement measuring unit 15measures the travel direction and traveled distance of the mobileterminal 1, starting from time T1, from sensor data received from thesensor unit 4 ((4) in FIG. 5).

When the positioning precision is then increased and error falls to orbelow a fixed threshold (1 meter, for example), the diameter of thedashed circle indicating the positioning precision is minimized ((5) inFIG. 5). The positioning time at which the diameter of the dashed circleis minimized is denoted by time T2.

The self-position identifying unit 14 then carries out compensation bysubtracting the amount of displacement continued until error inmeasurement using GPS signals has fallen within a prescribed range fromthe self-position measured when the positioning precision has fallenwithin a prescribed range. Specifically, to identify accuratecoordinates (latitude and longitude) of the self-position at time T1from the self-position at point Z at the time (=T2) at which GPS-basedpositioning has been completed, the self-position identifying unit 14performs an inverse operation on the relative travel direction andtraveled distance of the mobile terminal 1, which was measured andaccumulated by the displacement measuring unit 15 in the range from timeT1 to time T2.

FIG. 6 is a flowchart illustrating an example of processing in which themobile terminal 1 identifies its self-position at which positioning wasstarted.

First, the positioning managing unit 12 activates the GPS receiver 3 andstarts the determination of the self-position by the use of GPS. Thepositioning managing unit 12 then requires the self-position identifyingunit 14 to identify the self-position at time T1 (step S21).

Next, the self-position identifying unit 14 checks the positioning stateat the self-position (step S22). If positioning has been completed, theself-position identifying unit 14 acquires the self-position at time T1from the positioning managing unit 12 (step S23) and transfers theprocessing to step S29.

If positioning has not been completed, the positioning managing unit 12continues the determination of the self-position, and the displacementmeasuring unit 15 continues to measure the travel direction and traveleddistance of the mobile terminal 1, starting from point A at time T1(step S24). The self-position identifying unit 14 then decides whetherthe positioning completion flag is turned on or off to determine whetherthe state of GPS-based positioning by the positioning managing unit 12was updated and also determines GPS-based positioning precision (stepS25).

If the positioning completion flag is turned off and thereby theGPS-based positioning has not been completed, the sequence returns tostep S24 and the processing is repeated. If the positioning completionflag is turned on and thereby GPS-based positioning has been completed,and GPS precision is superior, the next process is carried out. At thattime, the current time is time T2, and the self-position identifyingunit 14 acquires, from the positioning managing unit 12, theself-position at time T2 as the first processing result (step S26).

Next, the self-position identifying unit 14 acquires, from thedisplacement measuring unit 15, the travel direction and traveleddistance of the mobile terminal 1 in the range from time T1 to time T2as a second processing result (step S27). The self-position identifyingunit 14 then calculates the self-position at point A at time T1 from theacquired first and second processing results (step S28).

The self-position identifying unit 14 then identifies that theself-position at time T1 is point A (step S29), terminating theprocessing.

FIG. 7 is a flowchart illustrating a detailed example of processing instep S24 in FIG. 6. Processing in steps S31 to S36 is the same as insteps S11 to S16 in FIG. 4, so its detailed description will be omitted.

After steps S31 to S36 have been executed, the positioning managing unit12 decides whether GPS-based positioning precision has exceeded theprescribed threshold (step S37). If GPS-based positioning precision hasexceeded the prescribed threshold, the positioning managing unit 12turns on the positioning completion flag (step S38). If GPS-basedpositioning precision has not exceeded the prescribed threshold, thepositioning managing unit 12 leaves the positioning completion flagturned off (step S39). The process in step S24 in FIG. 7 is thencompleted, and the sequence proceeds to step S25 in FIG. 6. Thus, itbecomes possible to identify the position of point A at whichpositioning was started from point Z determined when GPS-basedpositioning precision was sufficiently increased.

When the mobile terminal 1 according to the second embodiment describedabove cannot identify an accurate self-position at time T1 even by theuse of GPS, the mobile terminal 1 continues positioning until theself-position can be identified. After that, when GPS-based positioningprecision exceeds the prescribed threshold, the mobile terminal 1obtains the self-position at time T1 from the current self-position attime T2 and the travel direction and traveled distance detected by thesensor unit 4 in the range from time T1 to time T2. Accordingly, even ifan accurate self-position cannot be obtained at the start of positioningdue to low GPS precision, an accurate self-position at the start ofpositioning can be identified with high GPS precision by subsequentpositioning.

<3-1. Variation of the Method of Determining the Self-Position>

In the first and second embodiments described above, after the traveldirection and traveled distance, measured from time T1, of the mobileterminal 1 are accumulated in the memory 8, the self-position isobtained at time T2. However, an amount of displacement may be obtainedat prescribed time intervals before time T2 is reached, that is, even ifthe positioning completion flag remains turned off. A method ofdetermining the self-position in a third embodiment will be describedbelow.

FIGS. 8A and 8B illustrate an example in which the mobile terminal 1travels from point A to point Z. FIG. 8A illustrates an example of aroute along which the mobile terminal 1 travels from point A to point Z,and FIG. 8B illustrates an example of obtaining intermediate points bysegmenting the route from point A to point Z in a time-division manner.

Suppose a case in which the user captures an image at point A andtravels to point Z while carrying the mobile terminal 1, as illustratedin FIG. 8A. When traveling from point A to point Z, the user passespoints A1, A2, . . . , and An. The user determines the self-position atpoints A1, A2, . . . , and An at fixed time intervals.

After starting the determination of the self-position, the self-positionidentifying unit 14 repeats a process to accumulate, as an amount ofcompensation, a difference in an amount of displacement traveled in apredetermined time from a point at which the user was a predeterminedtime before, and uses the accumulated amount of compensation as theamount of displacement. Specifically, at point A1 (at time t1), theself-position identifying unit 14 obtains compensated coordinates ofpoint A1 from sensor data, acquired from the sensor unit 4, relative topoint A. The compensated coordinates can be obtained by the methodindicated in step S9 above in FIG. 3.

Next, at point A2, the self-position identifying unit 14 obtainscompensated coordinates of point A2 (time t2) from sensor data, acquiredfrom the sensor unit 4, relative to point A1. The self-positionidentifying unit 14 repeats similar processing to obtain compensatedcoordinates of point Z from sensor data, acquired from the sensor unit4, relative to point An (time tn). The self-position identifying unit 14then identifies point A, which is the self-position at the start ofpositioning, from the compensated coordinates obtained from time t1 toT2.

FIG. 8B illustrates the route from point A to pint Z as a straight line.At the points to which the user traveled while carrying the mobileterminal 1, compensated coordinates have been obtained at fixed timeintervals. If the sensor data acquired from the sensor unit 4 isdiscarded each time compensated coordinates are obtained at each point,an area in which to record the sensor data can be reduced in the memory8.

<4-1. First Display Example of a User Interface>

Display examples of a user interface will be described with reference toFIGS. 9A-9D and 10A-10C, the user interface being displayed on thedisplay unit 7 of the mobile terminal 1 in the first to thirdembodiments described above during the determination of theself-position.

FIG. 9 illustrates a first display example of the user interfacedisplayed on the display unit 7 during the determination of theself-position. FIG. 9A illustrates a display example when GPS-basedpositioning is disabled. FIG. 9B illustrates a display example whenGPS-based positioning is able to determine the self-position. FIG. 9Cillustrates a display example when GPS-based positioning enabled todetermine the self-position and operation is monitored by the sensorunit 4. FIG. 9D illustrates a display example when the determination ofthe self-position has been completed.

The positioning managing unit 12 displays, on the display unit 7, anicon indicating that positioning by the use of GPS signals is inprogress. With GPS-based positioning turned off, a menu button 7 a fordisplaying various menus, a camera button 7 b for switching to a camerafunction, an AF range frame 7 c for measuring a distance to a subjectduring an auto focus operation are displayed on the display unit 7 (FIG.9A).

When GPS-based positioning is turned on and the determination of theself-position is started, a GPS icon 7 d indicating that GPS signals arebeing received from GPS satellites and positioning state icon 7 eindicating that the self-position is being determined are turned on(FIG. 9B).

When, in response to a request to determine the self-position, which isthe position at time T1, the determination of the self-position iscontinued and the sensor unit 4 is being activated, a sensor monitoringicon 7 f is turned on. (FIG. 9C). When the determination of theself-position is completed at time T2 and the calculation of theself-position at time T1 is completed, the sensor monitoring icon 7 fdisappears and only the GPS icon 7 d remains displayed (FIG. 9D).

<4-2. Second Display Example of the User Interface>

FIGS. 10A-10C illustrate a second display example of the user interfacein a case in which the self-position at the time of imaging isdetermined with a captured image displayed. FIG. 10A illustrates anexample of an image displayed on the display unit 7 when imaging iscarried out at time T1, FIG. 10B illustrates an example of an imagedisplayed while determination is in progress, and FIG. 10C illustratesan example displayed at time T2 at which determination is completed.

When imaging is carried out, a GPS icon 7 g indicating that GPS-basedpositioning has been started, imaging information 7 h added to capturedimage data, and positioning information 7 i, about the self-position,obtained as a result of GPS-based positioning are first displayed on thedisplay unit 7 (FIG. 10A). In this case, the GPS icon 7 g is decolorizedand is represented with dashed lines. The imaging information 7 hincludes the date and time of imaging, and the positioning information 7i includes measurement error in GPS-based positioning and the latitudeand longitude at the point at which positioning was carried out at timeT1. The positioning information 7 i indicates that measurement error is30 meters at time T1, the latitude at the self-position is 35 degrees,41 minutes, 26 second north latitude, and the longitude is 139 degrees,44 minutes, 25 seconds east longitude.

When the user then travels with the image displayed, part of the GPSicon 7 g is colorized and one radio wave icon 7 j, which indicates thatGPS-based positioning is in progress, is displayed (FIG. 10B). At thattime, it is indicated that measurement error is 15 meters, the latitudeat the self-position is 35 degrees, 41 minutes, 26 second northlatitude, and the longitude is 139 degrees, 44 minutes, 25 seconds eastlongitude.

When GPS-based positioning is completed, the entire GPS icon 7 g iscolorized and the number of radio wave icons 7 j is increased to two(FIG. 10C). At that time, it is indicated that measurement error is 1meter, the latitude at the self-position is 35 degrees, 41 minutes, 27second north latitude, and the longitude is 139 degrees, 44 minutes, 25seconds east longitude. Accordingly, an accurate self-position at timeT1 is updated and the updated self-position is added to the image data.

<4-3. Second Display Example of the User Interface>

FIG. 11 illustrates a third display example of the user interface usedwhen the travel trace of the mobile terminal 1 is displayed on thedisplay unit 7. In the drawing, since positioning precision is low, atravel trace before the route was compensated is represented withdash-dot lines and a travel trace after the route was compensated isrepresented with solid lines. The dashed circle indicates GPS-basedpositioning precision.

When the mobile terminal 1 started the determination of theself-position, the position of point A is not accurate. As indicated inthe second embodiment above, when positioning precision is increasedafter a lapse of the predetermined time, however, the self-position atthe start of positioning can be identified. At that time, a trace alongwhich the user carrying the mobile terminal 1 traveled can be obtainedfrom the amount of displacement that the displacement measuring unit 15has acquired from the sensor unit 4. Accordingly, after theself-position was identified by the self-position identifying unit 14,the displacement measuring unit 15 can display, on the display unit 7, atravel trace between the self-position (point Z) after the travel andthe identified self-position (point A) at the start of positioning.

In this case, the identified self-position at the start of positioningand a travel trace to the self-position acquired from the positioningmanaging unit 12 after a lapse of the predetermined time may bedisplayed on the display unit 7, and information about an applicationprogram used within the prescribed time may also be displayed.Accordingly, when an accurate travel trace is displayed on the displayunit 7, behaviors (events) of the user carrying the mobile terminal 1during travel can also be displayed on the display unit 7 in conformitywith the travel trace.

The behaviors of the user include information indicating, for example,that what type of application program the user used and where the userused it and that what the user bought and where the user bought it.These information items are illustrated as events e1, e2, and e3together with marks indicating the occurrence of the events. Forexample, event e1 indicates that the user used a camera application tophotograph a subject, event e2 indicates that the user used a mapapplication to search for geographic information about the circumference(such as shops recommended through word of mouth), and event e3indicates that the user entered a shop and used a credit cardapplication of the mobile terminal 1 to do his or her shopping. An eventname is displayed at the lower-right of the display unit 7 for each ofevents e1 to e3. Therefore, the user not only can add positioninginformation to image data but also can add the user's behaviors at fixedtime intervals, starting from the start of photography, to the imagedata in association with it.

Furthermore, if information that identifies generated events and themobile terminal 1 is uploaded to an application server, which sendsprescribed information to the mobile terminal 1, together with thetravel trace of the mobile terminal 1, the application server cananalyze the behaviors of the user. Therefore, the application server cansend the mobile terminal 1 an application program recommended on thebasis of a history of user's behaviors and can cause the mobile terminal1 to give a display that promotes the use of the application program.Then, it becomes possible to display, on the display unit 7, informationcustomized according to the preference of the user.

The display examples of the user interface illustrated in FIGS. 9 to 11are used to notify the user of the state of each procedure in eachembodiment and to promote the completion of self-positionidentification, and do not limit the display method.

5. Variation

In the process to receive a GPS signal in step S12 in FIG. 4 and stepS32 in FIG. 7, there may be a case in which the GPS signal cannot bereceived when, for example, the user enters a dead space, in which themobile terminal 1 cannot communicate. Accordingly, a time to acquire GPSinformation may be a time before the user enters a dead space. Themobile terminal 1 conventionally measures communication intensity atfixed time intervals to change the display of an antenna icon accordingto the communication intensity. This enables a time to acquire a GPSsignal to be set to a time at which the communication intensity of themobile terminal 1 falls below a prescribed value.

Although the first to third embodiments described above have beenapplied to the mobile terminal 1 having a camera function as examples,they may be applied to a self-position measuring terminal that obtains auser's travel trace as described in the third display example of theuser interface. If a user having this type of self-position measuringterminal activates an application program that records a user's traveltrace in the terminal when the user goes jogging, walking, or the like,the user can make use of the recorded trace in user's health management.

Although the conventional geotag has information about a latitude andlongitude, a travel in height may be detected according to thedisplacement information acquired from the sensor unit 4. If, forexample, a route that also includes up and down stairways is recorded,more accurate positions to which the user traveled can be obtained.

When the user posts information about the current self-position, afavorite shop, or the like to Social Network Service (SNS), the user mayadd an identified position. Even in this use application, when themethod of identifying the self-position according to this disclosure isused, the user can send an accurate position to SNS even at a positionapart from the identified position. By comparison, in the conventionalpractice, the user must wait until the position is identified.

When a series of processes in the embodiments described above isexecuted by software, the series of processes can be executed by acomputer in which programs constituting the software have been embeddedin dedicated hardware or by a computer in which programs executingvarious functions have been installed. For example, the series ofprocesses can be executed by installing programs constituting desiredsoftware in, for example, a general-purpose personal computer.

A recording medium storing program code of software that implements thefunctions in the embodiments described above may be supplied to a systemor an apparatus. It will be appreciated that the functions can also beexecuted when a computer (or a CPU or another control unit) in thesystem or apparatus reads out and executes the program code stored inthe storage medium.

In this case, a flexible disk, hard disk, optical disk, magneto-opticaldisk, CD-ROM, CD-R, magnetic tape, non-volatile memory card, or ROM canbe used, for example, as the recording medium used to supply the programcode.

When the computer reads outs and executes the program code, thefunctions in the embodiments described above are implemented. Inaddition, an OS or the like running on the computer executes part or allof the actual processes in response to instructions from the programcode. A case in which the functions in the embodiments described aboveare executed by this processing is also included. The processes in theembodiments described above may be formed with hardware instead ofexecuting them with software.

It will be apparent that this disclosure is not limited to theembodiments described above and other various types of applicationexamples and variations are possible without departing from the intendedscope of this disclosure described in the claims. Accordingly, it willbe understood by those skilled in the art that various modification andcombinations and other elements may be derived from design or otherelements within the range of the claims or an equivalent range of theclaims.

This enclosure can also have structures as described below.

(1) An information processing apparatus comprising: a positioning unitthat determines a position of the information processing apparatus basedon an external signal; a sensor unit that detects a change in positionof the information processing apparatus; and a processing unit thatmeasures, according to a change in position detected at the sensor unit,an amount of displacement of the information processing apparatus from afirst time when the positioning unit starts to determine the position ofthe information processing apparatus to a second time when thepositioning unit completes determining the position of the informationprocessing apparatus; and identifies a position of the informationprocessing apparatus at the first time by compensating the position ofthe information processing apparatus determined by the positioning unitat the second time with the amount of displacement of the informationprocessing apparatus.

(2) The information processing apparatus of (1), wherein the processingunit identifies the position of the information processing apparatus atthe first time by subtracting the measured amount of displacement fromthe position of the information processing apparatus determined by thepositioning unit at the second time.

(3) The information processing apparatus of any of (1) to (2), whereinthe sensor unit comprises at least one of an electronic compass, anacceleration sensor and a gyro sensor.

(4) The information processing apparatus of any of (1) to (3), whereinthe sensor unit continuously detects the change in position of theinformation processing apparatus between the first time and the secondtime.

(5) The information processing apparatus of any of (1) to (4), whereinthe positioning unit is a Global Positioning Satellite (GPS) unit thatdetermines the position of the information processing apparatus based onexternally received GPS signals.

(6) The information processing apparatus of (5), wherein the processingunit is further configured to monitor a precision in the positiondetermined by the GPS unit.

(7) The information processing apparatus of (6), wherein the processingunit determines that the positioning unit completes determining theposition of the information processing apparatus when the precision inthe position determined by the GPS unit is within a predetermined range.

(8) The information processing apparatus of any of (1) to (7), furthercomprising: a display, wherein the processing unit controls the displayto display a graphic indicia indicating that the positioning unit isactively determining a position of the information processing apparatus.

(9) The information processing apparatus of (8), wherein the graphicindicia includes an image of a satellite.

(10) The information processing apparatus of any of (8) to (9), whereinthe processing unit controls the display to modify the graphic indiciawhen the positioning unit completes determining the position of theinformation processing apparatus.

(11) The information processing apparatus of any of (8) to (10), whereinthe processing unit controls the display to display a second graphicindicia indicating that the position of the information processingapparatus at the first time is in the process of being identified.

(12) The information processing apparatus of (11), wherein theprocessing unit controls the display to modify the second graphicindicia when the position of the information processing apparatus at thefirst position has been identified.

(13) The information processing apparatus of any of (1) to (12), furthercomprising: a display, wherein the processing unit controls the displayto display the position of the information processing apparatusdetermined by the positioning unit at the second time.

(14) The information processing apparatus of any of (1) to (13), furthercomprising: a display, wherein the processing unit controls the displayto display the position of the information processing apparatusidentified at the first time.

(15) The information processing apparatus of any of (1) to (14), furthercomprising: an image capturing unit that captures an image of a subject,wherein the processing unit adds information corresponding to theposition of the information processing apparatus identified at the firsttime to the captured image.

(16) The information processing apparatus of any of (1) to (15), furthercomprising: an image capturing unit that captures an image of subject;and a display, wherein the processing unit controls the display todisplay the position of the information processing apparatus determinedby the positioning unit at the second time or the position of theinformation processing apparatus identified at the first timesuperimposed on the captured image of the subject.

(17) The information processing apparatus of any of (1) to (16), furthercomprising: a display, wherein the processing unit controls the displayto display a trace linking the position of the information processingapparatus identified at the first time with the position of theinformation processing apparatus determined by the positioning unit atthe second time.

(18) A method performed by an information processing apparatus, themethod comprising: determining, by a position determining unit of theinformation processing apparatus, a position of the informationprocessing apparatus based on an external signal; detecting, by adetecting unit of the information processing apparatus, a change inposition of the information processing apparatus; measuring, accordingto a change in position detected by the detecting, an amount ofdisplacement of the information processing apparatus from a first timewhen the positioning unit starts to determine the position of theinformation processing apparatus to a second time when the positioningunit completes determining the position of the information processingapparatus; and identifying a position of the information processingapparatus at the first time by compensating the position of theinformation processing apparatus determined by the positioning unit atthe second time with the amount of displacement of the informationprocessing apparatus.

(19) A non-transitory computer-readable medium includingcomputer-program instructions, which when executed by an informationprocessing apparatus, cause the information processing apparatus toperform a process comprising: determining, by a position determiningunit of the information processing apparatus, a position of theinformation processing apparatus based on an external signal; detecting,by a detecting unit of the information processing apparatus, a change inposition of the information processing apparatus; measuring, accordingto a change in position detected by the detecting, an amount ofdisplacement of the information processing apparatus from a first timewhen the positioning unit starts to determine the position of theinformation processing apparatus to a second time when the positioningunit completes determining the position of the information processingapparatus; and identifying a position of the information processingapparatus at the first time by compensating the position of theinformation processing apparatus determined by the positioning unit atthe second time with the amount of displacement of the informationprocessing apparatus.

1. An information processing apparatus comprising: a positioning unitthat determines a position of the information processing apparatus basedon an external signal; a sensor unit that detects a change in positionof the information processing apparatus; and a processing unit thatmeasures, according to a change in position detected at the sensor unit,an amount of displacement of the information processing apparatus from afirst time when the positioning unit starts to determine the position ofthe information processing apparatus to a second time when thepositioning unit completes determining the position of the informationprocessing apparatus; and identifies a position of the informationprocessing apparatus at the first time by compensating the position ofthe information processing apparatus determined by the positioning unitat the second time with the amount of displacement of the informationprocessing apparatus.
 2. The information processing apparatus of claim1, wherein the processing unit identifies the position of theinformation processing apparatus at the first time by subtracting themeasured amount of displacement from the position of the informationprocessing apparatus determined by the positioning unit at the secondtime.
 3. The information processing apparatus of claim 1, wherein thesensor unit comprises at least one of an electronic compass, anacceleration sensor and a gyro sensor.
 4. The information processingapparatus of claim 1, wherein the sensor unit continuously detects thechange in position of the information processing apparatus between thefirst time and the second time.
 5. The information processing apparatusof claim 1, wherein the positioning unit is a Global PositioningSatellite (GPS) unit that determines the position of the informationprocessing apparatus based on externally received GPS signals.
 6. Theinformation processing apparatus of claim 5, wherein the processing unitis further configured to monitor a precision in the position determinedby the GPS unit.
 7. The information processing apparatus of claim 6,wherein the processing unit determines that the positioning unitcompletes determining the position of the information processingapparatus when the precision in the position determined by the GPS unitis within a predetermined range.
 8. The information processing apparatusof claim 1, further comprising: a display, wherein the processing unitcontrols the display to display a graphic indicia indicating that thepositioning unit is actively determining a position of the informationprocessing apparatus.
 9. The information processing apparatus of claim8, wherein the graphic indicia includes an image of a satellite.
 10. Theinformation processing apparatus of claim 8, wherein the processing unitcontrols the display to modify the graphic indicia when the positioningunit completes determining the position of the information processingapparatus.
 11. The information processing apparatus of claim 8, whereinthe processing unit controls the display to display a second graphicindicia indicating that the position of the information processingapparatus at the first time is in the process of being identified. 12.The information processing apparatus of claim 11, wherein the processingunit controls the display to modify the second graphic indicia when theposition of the information processing apparatus at the first positionhas been identified.
 13. The information processing apparatus of claim1, further comprising: a display, wherein the processing unit controlsthe display to display the position of the information processingapparatus determined by the positioning unit at the second time.
 14. Theinformation processing apparatus of claim 1, further comprising: adisplay, wherein the processing unit controls the display to display theposition of the information processing apparatus identified at the firsttime.
 15. The information processing apparatus of claim 1, furthercomprising: an image capturing unit that captures an image of a subject,wherein the processing unit adds information corresponding to theposition of the information processing apparatus identified at the firsttime to the captured image.
 16. The information processing apparatus ofclaim 1, further comprising: an image capturing unit that captures animage of subject; and a display, wherein the processing unit controlsthe display to display the position of the information processingapparatus determined by the positioning unit at the second time or theposition of the information processing apparatus identified at the firsttime superimposed on the captured image of the subject.
 17. Theinformation processing apparatus of claim 1, further comprising: adisplay, wherein the processing unit controls the display to display atrace linking the position of the information processing apparatusidentified at the first time with the position of the informationprocessing apparatus determined by the positioning unit at the secondtime.
 18. A method performed by an information processing apparatus, themethod comprising: determining, by a position determining unit of theinformation processing apparatus, a position of the informationprocessing apparatus based on an external signal; detecting, by adetecting unit of the information processing apparatus, a change inposition of the information processing apparatus; measuring, accordingto a change in position detected by the detecting, an amount ofdisplacement of the information processing apparatus from a first timewhen the positioning unit starts to determine the position of theinformation processing apparatus to a second time when the positioningunit completes determining the position of the information processingapparatus; and identifying a position of the information processingapparatus at the first time by compensating the position of theinformation processing apparatus determined by the positioning unit atthe second time with the amount of displacement of the informationprocessing apparatus.
 19. A non-transitory computer-readable mediumincluding computer-program instructions, which when executed by aninformation processing apparatus, cause the information processingapparatus to perform a process comprising: determining, by a positiondetermining unit of the information processing apparatus, a position ofthe information processing apparatus based on an external signal;detecting, by a detecting unit of the information processing apparatus,a change in position of the information processing apparatus; measuring,according to a change in position detected by the detecting, an amountof displacement of the information processing apparatus from a firsttime when the positioning unit starts to determine the position of theinformation processing apparatus to a second time when the positioningunit completes determining the position of the information processingapparatus; and identifying a position of the information processingapparatus at the first time by compensating the position of theinformation processing apparatus determined by the positioning unit atthe second time with the amount of displacement of the informationprocessing apparatus.